The present invention relates to a holder for freeze-drying of drug solutions. More particularly, the present invention relates to a holder for freeze-drying of drug solutions, which makes it possible to efficiently and precisely charge a predetermined amount of a drug solution into a container without any fear of contamination of drugs with foreign substances.
Lyophilization or Freeze-drying is a well-known method for drying drugs at low temperatures and at vacuum pressures, which makes it possible to produce drugs with very high solubility, without decreasing activities of the unstable drugs. Conventionally known methods for production of freeze-dried drugs include the following two methods:
I) A method comprising the steps of charging a drug solution into a container such as a glass vial, freeze drying the drug solution in a vacuum drying chamber, introducing aseptically filtered dry inert gas into the drying chamber, and then sealing the container with a plug; and
II) A method comprising the steps of freeze-drying a lot of drugs in a container such as a tray (commonly referred to as “tray drying”), pulverizing the resultant freeze-dried drugs, sieving the resultant powder to separate particles of a uniform size, and then charging the powder into the containers with a powder charger.
However, these conventional methods have advantages and problems to be solved. For this reason, one of the present inventors and other inventors proposed in an unexamined Japanese patent publication No. JP-A-H10-305083, a method for freeze drying of drugs, employing a flexible container or bag as a container for freeze-drying and also as a packaging container for freeze-dried drugs as it is. JP-A-H10-305083 also discloses a holder for freeze-drying of drugs (cf., FIG. 6), in which a pressure assembly 31 includes a bar 311 for closing an opening of the flexible container. In this method, the container or bag is closed by the bar 311 after freeze-drying, taken out of a freeze-drying chamber, and then sealed at an opening thereof by hot welding.
However, when sealing the opening of the flexible container by hot welding, there remains space, which may allow foreign substances or bacteria to invade into the interior of the container, between a sealing part of the container and the bar or within a freeze-dried drug-holding area inside the sealing portion. It has become apparent that the above problem results from the fact that the above holder has only one pressure bar.